1. Field of the Invention
The present invention generally relates to electronic apparatus and, in a preferred embodiment thereof, more particularly relates to cursor control systems for computers.
2. Description of Related Art
A variety of display screen cursor control systems have previously been utilized on or adjacent the keyboard portion of both desktop and portable computers. These cursor control devices include mice, trackballs, touchpads and pointing sticks.
The computer mouse is basically a small housing which has a ball on its underside that is rolled by the computer user along a horizontal support surface adjacent the keyboard in response to hand movement of the mouse housing parallel to the support surface. The sense and speed of the rotation of the mouse ball is monitored and appropriately converted to a positional output signal used to correspondingly reposition the cursor on the computer. The mouse housing typically has at least one "pick" button thereon which may be depressed to select an icon to which the cursor has been moved, or simply to select a desired screen location.
A track ball is basically an inverted mouse with the ball facing upwardly for direct manipulation by the computer user's fingers. The track ball is typically mounted on the base housing of a portable computer adjacent one or more "pick" buttons associated with the ball.
A touchpad typically has a small, generally planar rectangular surface along which the user runs his finger in the desired direction of cursor movement. A sensing structure beneath the user-engaged surface converts his finger movements to appropriate cursor movement signals. As in the case of the track ball and mouse, the touchpad is typically placed adjacent one or more manually depressible "pick" buttons.
A pointing stick is typically placed among and projects upwardly beyond a group of keyboard key cap members--usually in a generally central location of the keyboard between the user's index fingers in their "home" typing positions. Either index finger may be used to tilt the vertically oriented pointing stick in the desired direction of cursor movement, with a pressure sensing base portion of the pointing stick structure detecting the rocking movement of the stick and transforming the detected stick into corresponding cursor movement signals.
A recent potential addition to these types of cursor control devices, a two dimensional optical digitizer device, is illustrated and described in pending U.S. application Ser. No. 08/486,310, filed on Jun. 7, 1995, and pending U.S. application Ser. No. 08/651,881, filed on Jun. 4, 1996, each of such pending applications being assigned to the same assignee as this application. These digitizer devices utilize a single source of light to form a generally planar two dimensional light pattern disposed over and generally parallel to a computer keyboard. A finger placed in the light pattern interrupts a corresponding portion thereof, with the interruption location being sensed and used to transmit positional information to the display screen to selectively move a cursor thereon. A remote switch is used to activate this optically scanned cursor control mode, in which the movement of the user's hand in the scanned is used to correspondingly move the display screen cursor, and to return the keyboard to its typing mode.
Various problems, limitations and disadvantages are typically associated with these previously proposed types of cursor control devices and systems. It is to these problems, limitations and disadvantages that the present invention is directed.
For example, the computer mouse requires a substantial amount of unobstructed desktop space adjacent the keyboard to be moved around in. Also, many computer mice are configured for right hand use, making them awkward for the left-handed user. The trackball is typically integrated into the system keyboard area in a fixed location which is usually a compromise based on where there is space in the system. Accordingly, the trackball can often be somewhat awkward to use.
The touchpad, like the trackball, is typically integrated into a fixed area of the system keyboard structure. Additionally, the touchpad usually has a relatively small surface area along which the user's finger can be moved to correspondingly move the display screen cursor. Accordingly, the touchpad tends to be rather inconvenient to use when long cursor movements are required.
The pointing stick is the smallest of the conventionally utilized cursor positioning devices and thus may be very compactly located on the keyboard structure. However, the small size of this device makes it somewhat difficult for some users to properly engage and use cursor control and repositioning. Additionally, since the pointing stick is usually centrally located in the keyboard it often must be separated a substantial distance from its associated selection buttons. This, too, is often considered undesirable by computer users. Moreover, due to the "rocking" motion that must be imparted to the pointing stick to operate it, the use of the stick is considered by many users to be at least to some degree counterintuitive.
The optical digitizers mentioned above require for the generation and maintenance of their two dimensional optical fields above and generally parallel to the keyboard a variety of reflector, interceptor and light generating members mounted in exposed orientations on the keyboard. Additionally, these digitizer systems require, for a switchover between their typing and cursor control modes, that a control member located out of the sensing area of the optical scanning area be pressed and held down during the cursor control mode, and released when it is desired to return to the typing mode of the keyboard.
Like various other forms of cursor control associated with a computer keyboard, this requires the user to remove his hand or hands from the home row key position, thereby reducing the efficiency of using the keyboard and cursor device. Keeping the hands in the home row position is the main reason for having the cursor control device located over the keyboard. Having to manipulate a button or other control member located off the keyboard area, for either cursor positioning or selection operations, can be fatiguing and inconvenient, and can limit single hand operation of the cursor control device.
It would thus be desirable to provide apparatus which would enable a computer user to selectively and reliably switch between a typing and cursor control mode while maintaining his hands generally in their home row typing position above the keyboard, and move the display cursor and perform related pick functions while maintaining his hands above the keyboard.